Solve for $k$ : $-26 = -25 + k$
Solution: Add $25$ to both sides: $ \begin{eqnarray} \\ \hphantom{-26 {+ 25}} &\hphantom{=}& \hphantom{k} \\ -26 &=& -25 + k \\ \\ {+25} && {+25} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -26 {+ 25} &=& k \\ \end{eqnarray} $ Simplify. $ k = -1$